added some examples for the Accept-Encoding header
moved accept header parsing to a slightly better place
detect whether gzip is an accepted and preferred content encoding
Added a test for anorm
changed things as requested by pull request review
Merge pull request #1989 from asflierl/1983_correctly_handle_accept_encoding_gzip

correctly handle accept encoding gzip
Merge pull request #1992 from jroper/anorm-tests

Added a test for anorm
Merge pull request #1998 from baloo/improvements/826-Promise.flatMap

[#826] Make Promise.{flat,}map allow supertypes
Implement a redeemablePromise